Low loss GeO 2 doped silica waveguides for large scale integrated optical devices

TiO2 doped silica single-mode waveguides,1 produced by a combination of flame hydrolysis deposition (FHD) and reactive ion etching (RIE) on Si substrates, have been used in constructing various guided-wave optical devices. In some of these devices, such as ring resonators2 and multichannel optical frequency selection switches,3 the effective waveguide lengths reach several tens of centimeters. Therefore, the device performances are strongly restricted by a waveguide loss of around 0.3 dB/cm in the existing SiO2-TiO2 system. We give the first report (to our knowledge) on drastic loss reduction in long silica based waveguides by replacing TiO2 dopant with GeO2.